A Longitudinal Investigation of the Semantic Receptive-Expressive Gap in Spanish-English Bilingual Children.

Purpose: Although a semantic receptive-expressive gap appears to be a universal feature of early bilingualism, little is known about its development. We sought to determine if the magnitude of the discrepancy between receptive and expressive standard scores changed over time in bilingual children's two languages. Method: In this longitudinal study, standardized receptive and expressive semantics tests of 106 Spanish-English bilingual children with TD were taken at kindergarten and first grade in both English and Spanish. We used a multivariate analysis approach to identify interactions and main effects. Results: Although both receptive and expressive standard scores improved across the year in both languages, the magnitude of the gap was similar for both languages at both time points. However, there was greater improvement in English than in Spanish. Expressive scores at the end of the year were similar to receptive scores a year earlier. Conclusions: The magnitude of this gap remains relatively constant at kindergarten and first grade in both English and Spanish, despite overall improvements in semantic performance in both languages. There is on average roughly a one year lag between receptive and expressive semantics skills. Clinicians should take caution in interpreting receptive-expressive semantic gaps.

The Influence of Native- Versus Foreign-Accented Speech on Spanish-English Bilingual Children's Spanish Receptive Vocabulary Performance: A Pilot Study.

Purpose There are many fewer speech-language pathologists (SLPs) who can administer Spanish language testing than there are children in the United States who need such testing. Although there are precautions against language testing by foreign speakers, results from testers using native- versus foreign-accented speech have not been compared using popular picture-pointing vocabulary tests of the sort used by SLPs. Therefore, we sought to determine if nonnative Spanish speech (i.e., foreign-accented speech) was sufficient for the administration of a Spanish receptive vocabulary test. Method Using a single group, within-subjects design, 15 Spanish-English bilingual 5-year-olds from a low socioeconomic background listened to native- and foreign-accented digital audio recordings of targeted vocabulary words. Native- and foreign-accented testing was counterbalanced with a 2-month interlude. Using standard procedures, children were also administered English and Spanish-English bilingual picture-pointing vocabulary tests. Language histories were collected from caregivers and teachers. Results Standard scores were significantly lower for foreign- than for native-accented Spanish vocabulary testing. However, native-accented testing produced outcomes similar to those found in the literature for standard administration procedures. Conclusions Results support precautions that language testers should be proficient in the language of testing. However, standardized picture-pointing receptive vocabulary tests might be amenable to adaptations using recorded speech instead of standard procedures. This potentially extends the number of SLPs who might administer some Spanish testing.

Difficulties Using Standardized Tests to Identify the Receptive Expressive Gap in Bilingual Children's Vocabularies.

Receptive standardized vocabulary scores have been found to be much higher than expressive standardized vocabulary scores in children with Spanish as L1, learning L2 (English) in school (Gibson et al., 2012). Here we present evidence suggesting the receptive-expressive gap may be harder to evaluate than previously thought because widely-used standardized tests may not offer comparable normed scores. Furthermore monolingual Spanish-speaking children tested in Mexico and monolingual English-speaking children in the US showed other, yet different statistically significant discrepancies between receptive and expressive scores. Results suggest comparisons across widely used standardized tests in attempts to assess a receptive-expressive gap are precarious.

The Receptive-Expressive Gap in English Narratives of Spanish-English Bilingual Children With and Without Language Impairment.

Purpose: First, we sought to extend our knowledge of second language (L2) receptive compared to expressive narrative skills in bilingual children with and without primary language impairment (PLI). Second, we sought to explore whether narrative receptive and expressive performance in bilingual children's L2 differed based on the type of contextual support. Method: In a longitudinal group study, 20 Spanish-English bilingual children with PLI were matched by sex, age, nonverbal IQ score, and language exposure to 20 bilingual peers with typical development and administered the Test of Narrative Language (Gillam & Pearson, 2004) in English (their L2) at kindergarten and first grade. Results: Standard scores were significantly lower for bilingual children with PLI than those without PLI. An L2 receptive-expressive gap existed for bilingual children with PLI at kindergarten but dissipated by first grade. Using single pictures during narrative generation compared to multiple pictures during narrative generation or no pictures during narrative retell appeared to minimize the presence of a receptive-expressive gap. Conclusions: In early stages of L2 learning, bilingual children with PLI have an L2 receptive-expressive gap, but their typical development peers do not. Using a single picture during narrative generation might be advantageous for this population because it minimizes a receptive-expressive gap.

The Role of Lexical Stress on the Use of Vocal Fry in Young Adult Female Speakers.

OBJECTIVES: Vocal fry is a voice register often used by young adult women for sociolinguistic purposes. Some acoustic correlates of lexical stress, however, appear incompatible with the use of vocal fry. The objective of this study was to systematically examine the role of lexical stress in the use of vocal fry by young adult women. STUDY DESIGN: This is a semi-randomized controlled laboratory study. METHODS: Fifty female undergraduate students were recorded repeating one-, two-, three-, and four-syllable nonwords that conformed to English phonotactics. Nonwords were presented in order from shorter to longer lengths, with stimuli randomized within syllable length. Perceptual analyses of recordings were augmented by acoustic analyses to identify each syllable in which vocal fry occurred. RESULTS: Eighty-six percent of participants produced at least one episode of vocal fry. Vocal fry was more likely to occur in unstressed than stressed position, and the likelihood increased as distance from the stressed syllable increased. There was considerable variability in the use of vocal fry. Frequent and infrequent users varied on the degree to which they used vocal fry in single-syllable nonwords. CONCLUSIONS: Vocal fry use persists among young adult women even in the absence of syntactic and pragmatic influences. Lexical stress appeared to dramatically reduce the use of vocal fry. Patterns of vocal fry use appeared to be different for frequent and infrequent users of this vocal register.

Vocal Fry Use in Adult Female Speakers Exposed to Two Languages.

OBJECTIVE: Several studies have identified the widespread use of vocal fry among American women. Popular explanations for this phenomenon appeal to sociolinguistic purposes that likely take significant time for second language users to learn. The objective of this study was to determine if mere exposure to this vocal register, as opposed to nuanced sociolinguistic motivations, might explain its widespread use. STUDY DESIGN: This study used multigroup within- and between-subjects design. METHODS: Fifty-eight women from one of three language background groups (functionally monolingual in English, functionally monolingual in Spanish, and Spanish-English bilinguals) living in El Paso, Texas, repeated a list of nonwords conforming to the sound rules of English and another list of nonwords conforming to the sound rules of Spanish. Perceptual analysis identified each episode of vocal fry. RESULTS: There were no statistically significant differences between groups in their frequency of vocal fry use despite large differences in their amount of English-language exposure. All groups produced more vocal fry when repeating English than when repeating Spanish nonwords. CONCLUSIONS: Because the human perceptual system encodes for vocal qualities even after minimal language experience, the widespread use of vocal fry among female residents in the United States likely is owing to mere exposure to English rather than nuanced sociolinguistic motivations.

The role of phonological structure and experience in bilingual children's nonword repetition performance.

The current study examined the influence of phonological structure and language experience on the nonword repetition performance of bilingual children. Twenty-six Spanish-dominant and 26 English-dominant Spanish-English bilingual five-year-old children were matched on current exposure to the dominant language and year of first exposure to English. Participants repeated non-wordlike nonwords in English and Spanish. The Spanish-dominant group performed better than the English-dominant group for both Spanish and English nonwords. In addition, there was a main effect for test language, where Spanish nonwords were produced more accurately than English nonwords overall. The Spanish-dominant group advantage for nonwords is interpreted as emerging from the extra practice the dominant Spanish speakers had producing multisyllabic words.

The receptive-expressive gap in bilingual children with and without primary language impairment.

PURPOSE: In this study, the authors examined the magnitude of the discrepancy between standardized measures of receptive and expressive semantic knowledge, known as a receptive-expressive gap, for bilingual children with and without primary language impairment (PLI). METHOD: Spanish and English measures of semantic knowledge were administered to 37 Spanish-English bilingual 7- to 10-year old children with PLI and to 37 Spanish-English bilingual peers with typical development (TD). Parents and teachers completed questionnaires that yielded day-by-day and hour-by-hour information regarding children's exposure to and use of Spanish and English. RESULTS: Children with PLI had significantly larger discrepancies between receptive and expressive semantics standard scores than their bilingual peers with TD. The receptive-expressive gap for children with PLI was predicted by current English experience, whereas the best predictor for children with TD was cumulative English experience. CONCLUSIONS: As a preliminary explanation, underspecified phonological representations due to bilingual children's divided language input as well as differences in their languages' phonological systems may result in a discrepancy between standardized measures of receptive and expressive semantic knowledge. This discrepancy is greater for bilingual children with PLI because of the additional difficulty these children have in processing phonetic information. Future research is required to understand these underlying processes.

The relation between language experience and receptive-expressive semantic gaps in bilingual children.

The purpose of the current study was to explore the influence of language experience on the presence of the receptive-expressive gap. Each of 778 Spanish-English bilingual children screened pre-kindergarten in Utah and Texas were assigned to one of five language experience groups, ranging from functionally monolingual to balanced bilingual. Children's scores from the language screener semantics subtest administered in both Spanish and English were standardized, and receptive and expressive semantic scores were compared. Children presented with a meaningful gap between receptive and expressive semantic knowledge in English but not Spanish. This gap increased as target-language exposure decreased. Results indicate that current language experience plays a dominant role in influencing the appearance and magnitude of the receptive-expressive gap.

The receptive-expressive gap in the vocabulary of young second-language learners: Robustness and possible mechanisms.

Adults and children learning a second language show difficulty accessing expressive vocabulary that appears accessible receptively in their first language (L1). We call this discrepancy the receptive-expressive gap. Kindergarten Spanish (L1) - English (L2) sequential bilinguals were given standardized tests of receptive and expressive vocabulary in both Spanish and English. We found a small receptive-expressive gap in English but a large receptive-expressive gap in Spanish. We categorized children as having had high or low levels of English exposure based on demographic variables and found that the receptive-expressive gap persisted across both levels of English exposure. Regression analyses revealed that variables predicting both receptive and expressive vocabulary scores failed to predict the receptive-expressive gap. The results suggest that the onset of the receptive-expressive gap in L1 must have been abrupt. We discuss possible mechanisms underlying the phenomenon.

Improving evolutionary models of protein interaction networks.

MOTIVATION: Theoretical models of biological networks are valuable tools in evolutionary inference. Theoretical models based on gene duplication and divergence provide biologically plausible evolutionary mechanics. Similarities found between empirical networks and their theoretically generated counterpart are considered evidence of the role modeled mechanics play in biological evolution. However, the method by which these models are parameterized can lead to questions about the validity of the inferences. Selecting parameter values in order to produce a particular topological value obfuscates the possibility that the model may produce a similar topology for a large range of parameter values. Alternately, a model may produce a large range of topologies, allowing (incorrect) parameter values to produce a valid topology from an otherwise flawed model. In order to lend biological credence to the modeled evolutionary mechanics, parameter values should be derived from the empirical data. Furthermore, recent work indicates that the timing and fate of gene duplications are critical to proper derivation of these parameters. RESULTS: We present a methodology for deriving evolutionary rates from empirical data that is used to parameterize duplication and divergence models of protein interaction network evolution. Our method avoids shortcomings of previous methods, which failed to consider the effect of subsequent duplications. From our parameter values, we find that concurrent and existing existing duplication and divergence models are insufficient for modeling protein interaction network evolution. We introduce a model enhancement based on heritable interaction sites on the surface of a protein and find that it more closely reflects the high clustering found in the empirical network.

Reverse engineering the evolution of protein interaction networks.

Protein interaction network analyses have moved beyond simple topological observations to functional and evolutionary inferences based on the construction of putative ancestral networks. Evolutionary studies of protein interaction networks are generally derived from network comparisons, are limited in scope, or are theoretic dynamic models that aren't contextualized to an organism's specific genes. A biologically faithful network evolution reconstruction which ties evolution of the network itself to the actual genes of an organism would help fill in the evolutionary gaps between the gene network "snapshots" of evolution we have from different species today. Here we present a novel framework for reverse engineering the evolution of protein interaction networks of extant species using phylogenetic gene trees and protein interaction data. We applied the framework to Saccharomyces cerevisiae data and present topological trends in the evolutionary lineage of yeast.

Questioning the ubiquity of neofunctionalization.

Gene duplication provides much of the raw material from which functional diversity evolves. Two evolutionary mechanisms have been proposed that generate functional diversity: neofunctionalization, the de novo acquisition of function by one duplicate, and subfunctionalization, the partitioning of ancestral functions between gene duplicates. With protein interactions as a surrogate for protein functions, evidence of prodigious neofunctionalization and subfunctionalization has been identified in analyses of empirical protein interactions and evolutionary models of protein interactions. However, we have identified three phenomena that have contributed to neofunctionalization being erroneously identified as a significant factor in protein interaction network evolution. First, self-interacting proteins are underreported in interaction data due to biological artifacts and design limitations in the two most common high-throughput protein interaction assays. Second, evolutionary inferences have been drawn from paralog analysis without consideration for concurrent and subsequent duplication events. Third, the theoretical model of prodigious neofunctionalization is unable to reproduce empirical network clustering and relies on untenable parameter requirements. In light of these findings, we believe that protein interaction evolution is more persuasively characterized by subfunctionalization and self-interactions.